ITER’s best ally is in Japan and it is essential for nuclear fusion to be possible

On February 9, 2022, the largest operating European nuclear fusion reactor gave us a big surprise. That day the scientists carrying out experiments with it officially announced that they had succeeded in generating 59 megajoules of fusion energy for a period of 5 seconds. This milestone allowed JET (Joint European Torus), which is hosted in Oxford (England), to score a very important goal, but we must not forget that its essential task is to pave the way for ITER. This is what really makes it valuable.

However, there is another experimental nuclear fusion reactor using magnetic confinement even more ambitious than JET. And the experiments that it will allow to undertake during the next months will be crucial to bring ITER to a successful conclusion. This promising machine is called JT-60SA and is in Naka, a small town not far from Tokyo (Japan). At the beginning of last February we told you about it because the plasma tests will begin at the end of this year, but it is worth investigating the reasons why this machine is so important.

JT-60SA reactor will help optimize commercial fusion plants

The construction of this experimental nuclear fusion reactor began in January 2013. But it was not done from scratch; It did so taking as its starting point the JT-60 reactor, its precursor, a machine that came into operation in 1985 and that for more than three decades has reached very important milestones in the field of fusion energy. Assembly of the JT-60SA was completed in early 2020, and the intention of the Japanese and European scientists involved in its development was to start plasma testing as soon as possible. Finally they will arrive at the end of 2023and they will do it to deliver knowledge that will be very valuable in the development of ITER and DEMO.

The research plan designed by the scientists who operate the JT-60SA reactor defines five clearly differentiated phases of experimentation. The purpose of the first one is to demonstrate that the superconducting magnets that have the responsibility of confining the plasma at a very high temperature behave stably when a very high current is supplied to them. During this phase, the researchers will also carry out other fundamental checks, among which we can highlight the monitoring of the shape of the plasma and the analysis of the impurities that accumulate in the core of the reactor.

Very broadly, the next phase aims to study the behavior of the plasma, so it will be very important to determine if the stabilization strategies that will be implemented in ITER are adequate. When fully operational, the JT-60SA reactor will be capable of sustaining a deuterium nuclei plasma for a period of 100 s using a maximum current of 5.5 MA. ITER will be bigger than JT-60SAwhich in theory will allow you to reduce the loss of energy in the reactor core and will contribute to the stabilization of the plasma.

The third phase of experimentation at the Naka fusion reactor will try to recreate working conditions as similar as possible to those of ITER in order to accurately predict how the plasma will behave in the experimental reactor at Cadarache (France). This phase is similar to the previous one, but now the researchers will monitor very specific parameters that condition the behavior of the plasma, such as its intrinsic rotation or the effects that the energy of the particles has on the stabilization and confinement of the plasma.

The fourth phase of experimentation of the JT-60SA reactor aims, broadly speaking, to find the ideal operating parameters to optimize the behavior of the plasma in real time, minimize the loss of energy and solve the transport of impurities with guarantees. Finally, the fifth phase pursues mitigate potential risks derived from the ITER operation. If everything goes as expected by EUROfusion, the low power tests with hydrogen and helium in this last experimental reactor will begin in 2028, and the high power tests in 2032. The JT-60SA reactor will be a very valuable ally without which ITER will surely fail. it would be much more difficult.

Cover image: Fusion for Energy (F4E)

rmation: JT-60SA

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